怎么写findDNAMatches函数

写出一个findDNAMatches函数，返回s1和s2两条DNA链匹配的位置
怎么做呢？用kmp算法应该怎么写？

除了要求写的函数以外的代码已经给出

#include <iostream>
#include <string>
#include "console.h"
using namespace std;
 
/* Prototypes */
 
int findDNAMatch(string s1, string s2, int start = 0);
string matchingStrand(string strand);
void findAllMatches(string s1, string s2);
void getC(string s,int C[]);
 
/* Main program */
 
int main() {
   findAllMatches("TTGCC", "TAACGGTACGTC");
   findAllMatches("TGC", "TAACGGTACGTC");
   findAllMatches("CCC", "TAACGGTACGTC");
   return 0;
}
 
/*
 * Function: findAllMatches
 * Usage: findAllMatches(s1, s2);
 * ------------------------------
 * Finds all positions at which s1 can bind to s2.
 */
 
void findAllMatches(string s1, string s2) {
   int start = 0;
   while (true) {
      int index = findDNAMatch(s1, s2, start);
      if (index == -1) break;
      cout << s1 << " matches " << s2 << " at position " << index << endl;
      start = index + 1;
   }
   if (start == 0) {
      cout << s1 << " has no matches in " << s2 << endl;
   }
}
 
 
/*
 * Function: findDNAMatch
 * Usage: int pos = findDNAMatch(s1, s2);
 *        int pos = findDNAMatch(s1, s2, start);
 * ---------------------------------------------
 * Returns the first index position at which strand s1 would bind to
 * the strand s2, or -1 if no such position exists.  If the start
 * parameter is supplied, the search begins at that index position.
 */
 
 
int findDNAMatch(string s1, string s2, int start) {
    
    // [TODO: modify and fill in the code]
    return -1;
}